Network Access Security It's Broke, Now What? June 15, 2010

Transcription

1 Network Access Security It's Broke, Now What? June 15, 2010 Jeffrey L Carrell Network Security Consultant Network Conversions SHARKFEST 10 Stanford University June 14-17, 2010

2 Network Access Security It's Broke, Now What? Access Problems on the Network How to Solve It How to Enhance It Now it Works Now it s Broken

3 Network Access Security It's Broke, Now What? The Issue: Open Access LAN Switch Ports Authentication of Users and End-point Devices on a LAN Enhanced Policy Decisions after Initial Authentication Network Access Control/Protection Components of a Secure Access System Demonstration of an 802.1X System

4 The Issue: Open Access LAN Switch Ports Are there open or available LAN Switch ports? Can the client device get an IP address? Can the client gain any access to network? If so, then there is the possibility of network attacks attacks to network infrastructure devices (switches, APs) attacks to network resources (servers, etc) attacks to end-user computers virus, trojan, and other malware distribution use of network for malicious network attacks -inside and/or outside data privacy exploits

5 Controlling Access to the Network Lock down LAN switch ports with configuration that requires all connections to the switch to authenticate Users Authenticate providing userid/password credentials can be automated for single sign-on Devices Authenticate VoIP phones Printers Surveillance Cameras

6 Authentication of Users and End-point Devices on a LAN Authentication System for End-point Devices on a Local Area Network IEEE 802.1X The Challenge -Adding VoIP Phones to the Secure Network RFC-4675 Enhancements to IEEE 802.1X

7 What is IEEE 802.1X? IEEE 802.1X is a standards based mechanism allowing users and end-point devices to authenticate in order to gain network access Foundation relies on the Remote Authentication Dial- In User Service (RADIUS) networking protocol for Authentication, Authorization and Accounting (AAA) management Devices communicate via the Extensible Authentication Protocol over LAN (EAP-OL) -a Layer 2 communication to the authenticator

8 Why IEEE 802.1X? 802.1X controlled switch ports block normal traffic by default until authentication is verified using a RADIUS server and EAP For specific user authentication, RADIUS server can provide VLAN ID (VID) to switch 802.1X does not specify what EAP type is used, as long as the supplicant and authentication server agree on an EAP method 802.1X is an IEEE standard and therefore provides interoperability between standards-based network access equipment, authentication servers, and client supplicants

9 Components of an 802.1X System Supplicant Authenticator Authentication Clients 802.1X enabled AP Clients 802.1X enabled switch RADIUS User Database

10 Authentication Microsoft IAS (Windows 2000/2003) Microsoft NPS (Windows 2008) Juniper Networks Steel-Belted Radius (multiple server platforms) FreeRADIUS (many linux server platforms) Other RADIUS conforming to RFC s RFC 2284 PPP Extensible Authentication Protocol (EAP) RFC 2865 Remote Authentication Dial In User Service (RADIUS) RFC 2869 RADIUS Extensions * not an exhaustive list

11 Authenticator 802.1X Enabled LAN Switch 802.1X Enabled Wireless Access Point (generally requires enterprise-class devices)

12 Supplicant Microsoft WinXP, Vista, Win7 Apple Mac OS X Juniper Networks Odyssey Access Client (Windows, Red Hat Linux) Open Source - Open1X (Windows, Linux) Network Printers (built-in) VoIP Phones (built-in) LAN Switch (built-in) Wireless Access Point (built-in) Client MUST be configured for the same EAP type supported on the Authentication * not an exhaustive list

13 EAP types EAP-MD5 least secure most commonly supported on VoIP phones Protected EAP (EAP-PEAP) more secure, can use digital certificate on end-point EAP-Tunneled TLS (EAP-TTLS) more secure, can use digital certificate on end-point EAP-Transport Layer Security (EAP-TLS) most secure, requires digital certificate on end-point

14 802.1X Communications Flow Supplicant Authenticator Authentication Port is blocked (unauthorized) EAP Identity Request EAP Identity Response EAP Access Challenge EAP Identity Response EAP Success RADIUS Access Request RADIUS Access Challenge RADIUS Access Request RADIUS Access Accept Port is opened (authorized)

15 Switch Port States in 802.1X A port that has been configured to require 802.1X authentication has two states: Unauthorized no authorized client has connected to the port, or client has failed authentication Authorized connected client has supplied valid credentials and has been authenticated When a port is in the unauthorizedstate, only EAP traffic is allowed When a port is in the authorizedstate, traffic is forwarded normally

16 VLAN Assignment of Switch Port RADIUS can send attributes to the switch which could define a specific VLAN the port is assigned to based on the user credentials If RADIUS doesn t provide VLAN attributes, switch port could be assigned to authorized VID If RADIUS doesn t provide VLAN attributes and the authorized VID is not defined, then the switch opens the port using the statically assigned VID of that port * for the duration of that authorized users session

17 The Challenge -Adding VoIP Phones to the Secure Network Some manufacturers VoIP phones support 802.1X with a built-in supplicant, but generally only a few in their product lines if so, then a matching RADIUS remote access policy can be configured to support the VoIP phone Without RFC-4675, dynamic 802.1Q (tag) VID assignment from RADIUS is not possible If the VoIP phone doesn t have a supplicant, difficult to support 802.1X authentication some LAN switch manufacturers support alternate 802.1X authentication methods, such as MAC Auth & WEB Auth

18 RFC-4675 Enhancements to 802.1X RADIUS can specify tag ports (for VoIP phones) RADIUS can specify VLAN name to switch Is supported on: FreeRADIUS v May require LAN switch software upgrade

19 Configuring a Microsoft Based System for 802.1X Active Directory userid(s) must have remote access permission enabled IAS/NPS define each authenticator as RADIUS client define remote access policies for users LAN Switch and/or AP configure RADIUS server definition configure specific ports/wlans to support 802.1X Client Supplicant configure EAP type used for authentication

20 Enhanced Policy Decisions after Initial Authentication A mechanism to apply additional policy based rules to validate a user s level of access into the network Executes after initial 802.1X authentication Policy components may include: where is the user/device in the network when is the user/device on the network integrity of the computer or device

21 TCG/Microsoft/IETF Architectures What is it? Posture Collector Third-party software that runs on the client and collects TCG TNC Integrity Microsoft NAP System information on security status and applications, such as is A/V enabled and upto-date? Measureme Health nt Collector Agent Client Broker "Middleware" that runs on the client and talks to the Posture Collectors, collecting their data, and passing it down to Network Access Requestor. In product form, this is generally bundled with the Network Access Requestor. Network Access Requestor Software that connects the client to network. Examples might be 802.1X supplicant or IPSec VPN client. Used to authenticate the user, but also as a conduit for Posture Collector data to make it to the other side. TNC Client Network Access Requestor NAP Agent NAP Enforcement Client IETF NEA Posture Collector Posture Broker Client Posture Transport Client Posture Collector Client Broker Network Access Requestor Network Enforcement Point Posture Validator Broker Network Access Authority What is it? Network Enforcement Point Component within the network that TCG TNC Policy Microsoft NAP NAP enforces policy, typically an 802.1X-capable switch or WLAN, VPN Enforcement Enforcement gateway, or firewall. Point Posture Validator Third-party software that receives status information from Posture Collectors on clients and validates the status information against stated network policy, returning a status to the Broker. Broker "Middleware" acting as an interface between multiple Posture Validators and the Network Access Authority. Network Access Authority A server responsible for validating authentication and posture information and passing policy information back to the Network Enforcement Point. Integrity Measureme nt Verifier TNC Network Access Authority System Health Validator NAP Administration Network Policy IETF NEA Intermediar y Devices Posture Validator Posture Broker Posture Transport this slide from Interop ilabs NAC Team - used with permission

22 Enhanced Policy Decisions Example Policy Faculty User Faculty Access Policy Group Access Rule 1 full access for faculty user Class Room M-F 7A-6P Assigned Device Faculty WLAN Latest DEFs Access Profile VLAN 20 Settings QoS B/W Network Access Rule (ACL) access to faculty systems Network Access Rule (ACL) access to campus system Access Rule 2 limited access for faculty user Cafeteria Anytime Assigned Device Faculty WLAN Latest DEFs Access Profile VLAN 30 Settings QoS B/W Network Access Rule (ACL) no access to faculty systems Network Access Rule (ACL) access to campus system

23 Enhanced Policy Decisions Communications Flow Supplicant Authenticator Authentication with Radius Agent Port is blocked (unauthorized) EAP Identity Request EAP Identity Response EAP Access Challenge EAP Identity Response EAP Success RADIUS Access Request RADIUS Access Challenge RADIUS Access Request Policy Decision RADIUS Access modifies RADIUS Reply Accept Port is opened (authorized)

24 Network Access Control/Protection Before authentication and possible policy decision * Provides Endpoint Integrity Assessment Verify OS updates & hot fixes/service packs Verify security applications are running and up-to-date Provides Endpoint Integrity Enforcement Quarantines access for remediation to NAC/NAP policy compliance Restrict access for non-compliance * Some NAC/NAP Systems include these functions

25 Network Access Control/Protection 3 Primary client testing options Agent least user interaction ActiveX requires user to launch browser Agentless limited function 3 Types of Endpoint Integrity Assessment Tests Inline NAC/NAP server in the flow of traffic DHCP NAC/NAP server intercepts DHCP request 802.1X authentication required

26 Endpoint Integrity Assessment Test Inline NAC/NAP server in the flow of traffic NAC/NAP DHCP NAC/NAP Agent

27 Endpoint Integrity Assessment Test DHCP NAC/NAP server intercepts DHCP request NAC/NAP DHCP NAC/NAP Agent

28 Endpoint Integrity Assessment Test 802.1X Authentication required Authentication NAC/NAP Supplicant NAC/NAP Agent Authenticator User Database

29 Components of a Secure Access System Authentication Policy Enforcement NAC/NAP Supplicant NAC/NAP Agent Authenticator User Database

30 Demonstration of an 802.1X System Supplicant Authenticator Authentication Win X enabled switch RADIUS User Database Win7 Mitel 5212 ProCurve 3500yl-24G W2K8/NPS W2K8/AD

31 Of Course We Have Captures! Successful client authentication Failed client authentication

32 Successful Client Authentication, w/vlan Assignment

33 Successful Client Authentication, but Fail on Switch RADIUS provided VID, switch did not have that specific VID configured Fri Jun 04 13:44: : <12> Jun 4 13:44: dca: 8021X client, RADIUSassigned VID validation error. MAC E port 17 VLAN-Id 0 or unknown.

34 Unsuccessful Authentication: no Supplicant Enabled on Client

35 Fail-Client Configured for Incorrect EAP Type

36 Fail-Client Configured for Incorrect EAP Type Level Date and Time Source Event ID Task Category Information 06/13/ :33:38 Microsoft-Windows-Security-Auditing 6275 Network Policy "Network Policy discarded the accounting request for a user. Contact the Network Policy administrator for more information. User: Client Machine: NAS: RADIUS Client: Security ID: NULL SID Account Name: procurve Account Domain: - Fully Qualified Account Name: - Security ID: NULL SID Account Name: - Fully Qualified Account Name: - OS-Version: - Called Station Identifier: - Calling Station Identifier: B D8 NAS IPv4 Address: NAS IPv6 Address: - NAS Identifier: ProCurve_3524G NAS Port-Type: - NAS Port: 13 Client Friendly Name: ProCurve_3524G_a Client IP Address: Authentication Details: Proxy Policy Name: - Network Policy Name: - Authentication Provider: - Authentication : server01.traversalabs.com Authentication Type: - EAP Type: - Account Session Identifier: Reason Code: 49 Reason: connection attempt did not match any connection request policy. " The

37 Fail-No Client Defined in RADIUS for this Authenticator

38 Fail-no Radius Connection Policy Match

39 Fail-no Radius Network Policy Match

40 Captures Isn t All So, where can you look to troubleshoot if the captures don t tell the whole story? Look at RADIUS logs Event Viewer in W2K0/3/8 Look at switch logs Look at client Logs Event Viewer

41 Network Access Security It's Broke, Now What? Thank You for Attending! Jeffrey L Carrell Network Security Consultant jeff.carrell@networkconversions.com